The objective of this project is to develop and apply nuclear magnetic resonance for elucidating molecular structures and for studying the interactions within and between molecules in making contribution to the solution of various chemical problems. Various nmr techniques have been employed 1) to determine absolute stereochemistries of the 5,6-oxide formed from 7,12-dimethylbenz[a]-anthracene by cytochrome P450c and benzo[c] phenanthrene 5,6-oxide and other K-region derivatives; 2) to elucidate the structures of eight principal adducts formed from the deoxyguanosine residues of DNA upon relation in vitro with four configurationally isomeric benzo[c]phenanthrene 3,4-diol-1,2-epoxides; and 3) to demonstrate that tryptophan synthase can racemize the carbon of 5-fluoro-L-tryptphan and its 2,3-dihydro derivatives.